ABI: sysfs-bus-usb: better document variable argument

On almost all ABI documents, variable arguments are declared
as <foo_bar>. Change it here too, in order to allow replacing
such wildcards by regexes on a scriptable way.
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Acked-by: Rajat Jain <rajatja@google.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/2f7e4e874677dbd82693a6b219decefa18802e8f.1631782432.git.mchehab+huawei@kernel.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-bus-usb

@@ -166,14 +166,14 @@ Description:
 		The file will be present for all speeds of USB devices, and will
 		always read "no" for USB 1.1 and USB 2.0 devices.
 
-What:		/sys/bus/usb/devices/.../(hub interface)/portX
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>
 Date:		August 2012
 Contact:	Lan Tianyu <tianyu.lan@intel.com>
 Description:
-		The /sys/bus/usb/devices/.../(hub interface)/portX
+		The /sys/bus/usb/devices/.../<hub_interface>/port<X>
 		is usb port device's sysfs directory.
 
-What:		/sys/bus/usb/devices/.../(hub interface)/portX/connect_type
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/connect_type
 Date:		January 2013
 Contact:	Lan Tianyu <tianyu.lan@intel.com>
 Description:
@@ -182,7 +182,7 @@ Description:
 		The file will read "hotplug", "hardwired" and "not used" if the
 		information is available, and "unknown" otherwise.
 
-What:		/sys/bus/usb/devices/.../(hub interface)/portX/location
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/location
 Date:		October 2018
 Contact:	Bjørn Mork <bjorn@mork.no>
 Description:
@@ -192,7 +192,7 @@ Description:
 		raw location value as a hex integer.
 
 
-What:		/sys/bus/usb/devices/.../(hub interface)/portX/quirks
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/quirks
 Date:		May 2018
 Contact:	Nicolas Boichat <drinkcat@chromium.org>
 Description:
@@ -216,7 +216,7 @@ Description:
 		   used to help make enumeration work better on some high speed
 		   devices.
 
-What:		/sys/bus/usb/devices/.../(hub interface)/portX/over_current_count
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/over_current_count
 Date:		February 2018
 Contact:	Richard Leitner <richard.leitner@skidata.com>
 Description:
@@ -230,10 +230,10 @@ Description:
 		Any time this value changes the corresponding hub device will send a
 		udev event with the following attributes::
 
-		  OVER_CURRENT_PORT=/sys/bus/usb/devices/.../(hub interface)/portX
+		  OVER_CURRENT_PORT=/sys/bus/usb/devices/.../<hub_interface>/port<X>
 		  OVER_CURRENT_COUNT=[current value of this sysfs attribute]
 
-What:		/sys/bus/usb/devices/.../(hub interface)/portX/usb3_lpm_permit
+What:		/sys/bus/usb/devices/.../<hub_interface>/port<X>/usb3_lpm_permit
 Date:		November 2015
 Contact:	Lu Baolu <baolu.lu@linux.intel.com>
 Description: